Wimbleball Leakage Reduction Programme

We have recently been involved in a project to remediate the leakage at Wimbleball Dam. The dam is located in the county of Devon and is jointly owned by South West Water Ltd and Wessex Water Ltd. The dam has leaked from its foundations since commissioning in 1979 and works have now been commissioned by the owners to remediate the leakage.

The works will consist of drilling a series of boreholes into the foundation strata beneath the dam and injecting high strength/ high penetrability liquid cement grouts to block the natural fissures in the bedrock through which the leakage is flowing. The dam will not be emptied for the works and will operate as normal.

It was expected that during works, leakage flows will become contaminated with drill flushings during drilling and cement from the grouts during their injection and these contaminated flows must be treated, as they eventually join the downstream water release flows from the dam. These contaminated flows must be directed to treatment plants. To complicate things there is a fish farm less than 0.5km downstream of the dam itself.

RS Hydro were contracted to provide a complex real-time water quality monitoring network to provide an automated alarm system if any of the grout from the remediation project was entering the water course.

The solution involved using 5 Manta 2 multiparameter water quality sondes measuring optical dissolved oxygen, electrical conductivity, pH, REDOX/ORP, turbidity and depth. Each Manta 2 was hooked up to a radio telemetry unit which uploaded the data every 15 minutes 24/7. Each telemetry unit was powered by a small solar panel.

To read the full case study and learn more about the real-time monitoring solution please click here.